The invention concerns a process for the fluid-fluid extraction of gallium, germanium, or indium from an acid or base hydrous solution, as well as the pH-controlled precipitation out of the re-extraction solution for the recovery of a Ga-, Ge-, or In-concentrate.
Gallium, germanium, and indium are important raw materials in the semi-conductor industry. Gallium is also used in the technology of super conductors and magnetic materials, as material in lasers, as as well as a catalyst in chemical reactions. Germanium is used as a doping material in SiO.sub.2 -light wave conductors, and, above all else, in ultraoptics, as well as as a detector material. Indium has versatile use possibilities in base metals, specialized solders, magnetic materials in high-frequency technology and transistor manufacturing, as well as in salts in the lamp, glass, and ceramics industry or as a component of metallic components in the measuring, condensor, thermistor and infrared industries.
Common to these metals is the presence in only slight concentrations and as accompanying minerals of a aluminum, lead, copper, and zinc ores. Thus, Ga, Ge, and In accumulate, in greater or lesser concentrations, in intermediate or waste products in the metallurgy of these base metals. They have particular significance for the concentration stages of the extraction process. Lyeing, precipitating, cementation, adsorption, chlorination and electrolysis processes, as well as the use of ion exchangers, have been developed.
The use of solvent extraction agents, which work as selectively as possible, can also lead to favorable concentrations in the re-extraction solution or intermediate product, if high extraction capacity and re-extraction capacity exist.
Thus, it is known from DOS 24 23 355, for example, to use the oxime 19-hydroxyhexatriaconta-9,28-diene 18-oxime dissolved in an organic solvent for the extraction of germanium.
The use of a substituted 8-hydroxyquinoline as an extraction agent, which is dissolved in an organic solvent and is to be used at specific temperatures, is described in the European Patent No. 68,541.
One disadvantage in the use of a compound such as cited in the state of the art is the tendency of such compounds to bind with other metal ions, such as Cu, for example, and in differing quantities according to the raw material and its concentrations, and to thus be insufficiently selective. Therefore, Cu must, for example, be eliminated by means of a special process, for example, cementation in the acidic medium. In such a solvent extraction process, the phase separation is frequently so slow that the process is made difficult and uneconomical.
It is the task of the present invention to propose a process of the type described above for a solvent extraction by using hydroxyquinolines, which is more advanced and has an improved selectivity as well as capacity for the elements named, which has a more rapid phase separation, and which makes possible an optimal adjustment of the density and viscosity of the organic phase, with consideration to the other process parameters.